What is presystemic drug elimination?

Question

Presystemic drug elimination is:

Answer choices

1. Inactivation in the small-intestinal mucosa and liver during the first pass.
2. Inactivation after the drug has exerted its pharmacological effect.

Explanation

Presystemic elimination reduces the amount of a substance that reaches the systemic circulation after absorption. For an orally administered drug, metabolism in the intestinal wall and liver before it enters the systemic circulation is particularly relevant.

The answer therefore concerns the first pass, rather than inactivation only after a pharmacological effect has occurred. The extent of this process affects bioavailability.